Download for reference Name Period ______ Date ______ Motion Notes from

for reference
Name _______________________________________ Period __________ Date ___________
Motion Notes from science class. Use this as a study guide.
Motion: a change in position, measured by distance and time.
Frame of reference: the point from which movement is determined.
 To measure movement, some point must be considered as nonmoving.
 Earth is the most common frame of reference.
Speed: the distance traveled by a moving object per unit of time.
 To calculate speed, use this equation: Speed = distance / time
 Speed only specifies distance and time, not direction.
Average speed: the speed of moving objects is not always constant, so:
 Average speed = total distance / total time
Velocity: speed in a given direction.
 Velocity specifies distance, time, and the direction of travel.
Acceleration: The rate of change in velocity.
 To calculate acceleration, use this equation:
Acceleration = (Final Velocity) - (Original Velocity) / Time
Deceleration: A term commonly used to mean a decrease in speed.
Force: any push or pull.
 Forces cause a change in motion.
Friction: a force that opposes motion. Friction occurs between two surfaces that are touching, e.g. between
air and a moving baseball.
Gravity: the force of attraction among all objects in the universe.
 Gravity is strong enough to be noticeable when massive objects like stars and planets are involved.
Free fall - an object falling under the influence of gravity.
 Near the surface of Earth all objects are accelerated by gravity at a rate of 9.8 m/s/s .*
Weight: the effect of gravity on an object’s mass
Momentum: mass x velocity: the product of an object’s mass and its velocity. (Think of momentum as
moving inertia.)
 All moving objects have momentum.
 To calculate momentum, use the equation: Momentum = Mass x Velocity
The Three Laws of Motion (by Sir Isaac Newton) explain all aspects of motion.
1. Newton's First Law (inertia) describes motion produced by balanced forces.
 An object at rest will remain at rest, and a moving object will remain at a constant velocity
unless unbalanced forces act on it.
 Newton was first to use the term inertia to describe the tendency of objects to remain in
motion or stay at rest. Inertia comes from the Latin word iners, which means "lazy".
2. Newton's Second Law describes motion produced by unbalanced forces.
 This law is best stated using this equation:
Force = mass X acceleration
Vocabulary (short list)
 Acceleration is always in the direction of the unbalanced
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Newton’s laws
force.
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momentum/ inertia
 The units of force are "newtons", symbol is N.
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work
 1 N = 1 kg X 1 m/s/s *
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force
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acceleration
3. Newton's Third Law explains why forces act in pairs.
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speed
 For every action, there is an equal and opposite reaction.
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time
 Forces always act in pairs.
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distance
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mass
*You are not expected to memorize 9.8 m/s/s. You do not have to memorize 1 kg X 1 m/s/s, either.
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velocity
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force
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center of mass
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balanced forces
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unbalanced forces